[ccoventry]

Release note: New: Render Settings can save clips as ProRes 422 (about 2/3 the size of HQ, now the default for new installs), ProRes 422 LT (about half) or ProRes 4444 (full colour detail, about 1.5x), with a line under the Codec picker saying what each is for. Existing settings keep their codec.

What changed

• Three new Render codecs beside ProRes 422 HQ, in Render Settings' Codec picker and in the three "When a batch finishes" pickers. ProRes 422 is listed first:

  Choice	Saved as	FFmpeg	Container
  ProRes 422 (2/3 the size of HQ), default for new installs	prores_422	prores_ks -profile:v standard -pix_fmt yuv422p10le	.mov
  ProRes 422 HQ	prores	-profile:v hq -pix_fmt yuv422p10le	.mov
  ProRes 422 LT (half the size of HQ)	prores_lt	-profile:v lt -pix_fmt yuv422p10le	.mov
  ProRes 4444 (1.5x the size of HQ)	prores_4444	-profile:v 4444 -pix_fmt yuv444p10le (no alpha)	.mov

• Default for new installs is ProRes 422; saved settings keep theirs. "render_codec": "prores" in an existing settings file, preset or autosave still means HQ (RenderCodec::ProRes keeps its name and id), and any other saved codec stays as it is. Only a missing or empty value gets 422: default_render_codec() (serde default and fresh AppSettings), RenderConfig::default(), RenderCodec::from_str_id's fallback for an empty or unknown id, and the JS fallbacks (render_pane.js, settings_sync.js, finish_clips.js, render_presets.js). No settings migration: nobody's existing renders change size without choosing to.

• HQ's -profile:v 3 is now written hq: the same profile. The HUD stream is untouched: always ProRes 4444 with alpha, whichever ProRes is picked.

• A one-line hint under the Codec picker (studio/src/codec_hint.js) that changes with the selection, for the four ProRes choices only:

  • 422: "Recommended for most videos: looks the same as HQ in our tests, about 2/3 the size."
  • HQ: "Looks the same as the capture; the largest of the three 422 choices, for when file size is no concern."
  • LT: "About half the size of HQ. Fine for game footage; a little more detail is lost in fast motion and fine textures."
  • 4444: "Full colour detail, about 1.5x the size of HQ. Only worth it for heavy colour grading or small coloured text drawn into the picture. No transparency: the separate HUD stream always has its own."

• Space reservation: each profile learns its own bytes per frame (its own RateKey). Until one has finished a render at a frame size, it borrows another ProRes profile's measured rate through their size ratios (HQ 1.0, 422 0.67, LT 0.47, 4444 1.5, in RenderCodec::prores_profile) instead of falling back to the raw-frame estimate. Other codecs and the HUD stream don't borrow.

• Combine Clips now also compares the codec tag (apch/apcn/apcs/ap4h), so HQ and 422 clips, which share codec and pixel format, are re-encoded rather than stream-copied into one file that would label every frame with the first clip's profile. This matters more now that new installs render 422 and older clips are HQ.

• docs/features.md: the codec table (422 as default) and a paragraph on which ProRes to pick.

Measurements

300 fps 2560x1440 capture (local\review-images\prores-compare\), one recorder (m00cat), one clip:

Profile	Size vs HQ	VMAF vs lossless
HQ	100% (0.51 GB/s)	99.3
422	67%	98.6
LT	47%	97.2
4444	147% (re-encoded from the HQ file, so slightly low)	not measured

No visible difference at 3x zoom between HQ, 422 and LT. Apple's target rates give the same ratios (147/220 = 0.67, 102/220 = 0.46, 330/220 = 1.5). On a generated testsrc2 2560x1440 Ut Video clip the ratios were 0.74 / 0.58 / 1.39: synthetic footage, so the defaults follow the real capture.

Tests

• New: config::tests::old_prores_values_still_mean_hq, each_prores_choice_has_its_own_profile, test_from_str_id_unrecognized_falls_back_to_prores_422 (also empty id and RenderConfig::default), the string-id and serde round trip over every codec; settings_manager::tests::a_fresh_install_renders_prores_422_and_a_saved_codec_stays and the legacy-file test (no render_codec → 422); renderer::tests::each_prores_choice_renders_with_its_own_profile (FFmpeg args per profile), a_prores_profile_borrows_another_profiles_rate_until_it_has_its_own; combine::tests HQ vs 422 not stream-copied; codec_hint.test.js; JS fallbacks in finish_clips.test.js and render_presets.test.js; an e2e check in render-studio.spec.js that 422 is first, the hint follows the picker and HQ's hint no longer says "default".
• New, #[ignore]d (needs FFmpeg): renderer::tests::prores_choices_render_with_their_profile generates a 2560x1440 300 fps Ut Video take with a wav, renders it through run_render_job with each ProRes choice, and checks ffprobe's profile= (HQ / Standard / LT / 4444). Run locally with DOD_FFMPEG=<ffmpeg.exe>: passed, all four profiles as expected.
• cargo test --locked --workspace, rustup run 1.98.1 cargo clippy --workspace --all-targets -- -D warnings, rustup run 1.98.1 cargo fmt --all --check: all pass (no failures; clippy clean).
• npm run test:unit: 914 passed. e2e render-studio, finish-clips, render-presets, app-boot: 71 passed.

Other open PRs touching the same files

#716 (renderer.rs, render_manager.rs, index.html, strings.js, features.md), #874 (index.html, strings.js, features.md), #881 and #832 (strings.js, features.md), #879, #760, #425 (strings.js). None touch the codec lines.

Decisions

• Option labels stay short with the size next to HQ; the longer advice is in the hint, not the label, so the capture summary's "Finish: …" line stays readable.
• ProRes 422 is the default for new installs and the first option (the user's pick); existing settings are not migrated.
• An empty or unknown codec id falls back to 422 too, the same as a missing one.
• The ids are prores_422, prores_lt, prores_4444.

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